Astro Integration API

Astro Integrations add new functionality and behaviors for your project with only a few lines of code.

This reference page is for anyone writing their own integration. To learn how to use an integration in your project, check out our Using Integrations guide instead.

The official Astro integrations can act as reference for you as you go to build your own integrations.

interface AstroIntegration {
    name: string;
    hooks: {
        'astro:config:setup'?: (options: {
            config: AstroConfig;
            command: 'dev' | 'build';
            updateConfig: (newConfig: Record<string, any>) => void;
            addRenderer: (renderer: AstroRenderer) => void;
            injectScript: (stage: InjectedScriptStage, content: string) => void;
        }) => void;
        'astro:config:done'?: (options: { config: AstroConfig }) => void | Promise<void>;
        'astro:server:setup'?: (options: { server: vite.ViteDevServer }) => void | Promise<void>;
        'astro:server:start'?: (options: { address: AddressInfo }) => void | Promise<void>;
        'astro:server:done'?: () => void | Promise<void>;
        'astro:build:start'?: (options: { buildConfig: BuildConfig }) => void | Promise<void>;
        'astro:build:setup'?: (options: {
          vite: ViteConfigWithSSR;
          pages: Map<string, PageBuildData>;
          target: 'client' | 'server';
        }) => void | Promise<void>;
        'astro:build:ssr'?: (options: { manifest: SerializedSSRManifest }) => void | Promise<void>;
        'astro:build:done'?: (options: { pages: { pathname: string }[]; dir: URL }) => void | Promise<void>;
    };
}

Next hook: astro:config:done

When: On initialization, before either the Vite or Astro config have resolved. Why: To extend the project config. This inludes updating the Astro config, applying Vite plugins, adding component renderers, and injecting scripts onto the page.

'astro:config:setup'?: (options: {
    config: AstroConfig;
    command: 'dev' | 'build';
    updateConfig: (newConfig: Record<string, any>) => void;
    addRenderer: (renderer: AstroRenderer) => void;
    injectScript: (stage: InjectedScriptStage, content: string) => void;
}) => void;

Type: AstroConfig

A read-only copy of the user-supplied Astro config. This is resolved before any other integrations have run. If you need a copy of the config after all integrations have completed their config updates, see the astro:config:done hook.

Type: 'dev' / 'build'

  • dev - Project is executed with astro dev or astro preview
  • build - Project is executed with astro build

Type: (newConfig: Record<string, any>) => void;

A callback function to update the user-supplied Astro config. Any config you provide will be merged with the user config + other integration config updates, so you are free to omit keys!

For example, say you need to supply a Vite plugin to the user’s project:

import bananaCSS from '@vitejs/official-banana-css-plugin';

export default {
  name: 'banana-css-integration',
  hooks: {
    'astro:config:setup': ({ updateConfig }) => {
      updateConfig({
        vite: {
          plugins: [bananaCSS()],
        }
      })
    }
  }
}

Type: (renderer: AstroRenderer ) => void; Examples: lit, svelte, react, preact, vue, solid

A callback function to add a component framework renderer (i.e. React, Vue, Svelte, etc). You can browse the examples and type definition above for more advanced options, but here are the 2 main options to be aware of:

  • clientEntrypoint - path to a file that executes on the client whenever your component is used. This is mainly for rendering or hydrating your component with JS.
  • serverEntrypoint - path to a file that executes during server-side requests or static builds whenever your component is used. These should render components to static markup, with hooks for hydration where applicable. React’s renderToString callback is a classic example.

Type: (stage: InjectedScriptStage, content: string) => void;

A callback function to inject a string of JavaScript content onto every page.

The stage denotes how this script (the content) should be inserted. Some stages allow inserting scripts without modification, while others allow optimization during Vite’s bundling step:

  • "head-inline": Injected into a script tag in the <head> of every page. Not optimized or resolved by Vite.
  • "before-hydration": Imported client-side, before the hydration script runs. Optimized and resolved by Vite.
  • "page": Similar to head-inline, except that the injected snippet is handled by Vite and bundled with any other <script> tags defined inside of Astro components on the page. The script will be loaded with a <script type="module"> in the final page output, optimized and resolved by Vite.
  • "page-ssr": Injected into the frontmatter of every Astro page component. This is not commonly used, however it can be useful for injecting a CSS import into every page via its frontmatter, optimized and resolved by Vite.

Previous hook: astro:config:setup Next hook: astro:server:setup when running in “dev” or “preview” mode, or astro:build:start during production builds

When: After the Astro config has resolved and other integrations have run their astro:config:setup hooks. Why: To retrieve the final config for use in other hooks.

'astro:config:done'?: (options: { config: AstroConfig }) => void | Promise<void>;

Type: AstroConfig

A read-only copy of the user-supplied Astro config. This is resolved after other integrations have run.

Previous hook: astro:config:done Next hook: astro:server:start

When: Just after the Vite server is created in “dev” or “preview” mode, but before the listen() event is fired. See Vite’s createServer API for more. Why: To update Vite server options and middleware.

'astro:server:setup'?: (options: { server: vite.ViteDevServer }) => void | Promise<void>;

Type: ViteDevServer

A mutable instance of the Vite server used in “dev” and “preview” mode. For instance, this is used by our Partytown integration to inject the Partytown server as middleware:

import

'astro:server:setup': ({ server }) => {
  server.middlewares.use(
    partytownServer(partytownLibDirectory, {
      mount: '/~partytown',
      ...
    })
  );
}

Previous hook: astro:server:setup Next hook: astro:server:done

When: Just after the server’s listen() event has fired. Why: To intercept network requests at the specified address. If you intend to use this address for middleware, consider using astro:server:setup instead.

'astro:server:start'?: (options: { address: AddressInfo }) => void | Promise<void>;

Type: AddressInfo

The address, family and port number supplied by the NodeJS Net module.

Previous hook: astro:server:start

When: Just after the dev server is closed. Why: To run any cleanup events you may trigger during the astro:server:setup or astro:server:start hooks.

'astro:server:done'?: () => void | Promise<void>;

Previous hook: astro:config:done Next hook: astro:build:setup

When: After the astro:config:done event, but before the production build begins. Why: To set up any global objects or clients needed during a production build. This can also extend the build configuration options in the experimental adapter API.

'astro:build:start'?: (options: { buildConfig: BuildConfig }) => void | Promise<void>;

Previous hook: astro:build:start Next hook: astro:build:ssr

When: After the astro:build:start hook, runs immediately before the build. Why: At this point, the Vite config for the build has been completely constructed, this is your final chance to modify it. This can be useful for example to overwrite some defaults. If you’re not sure whether you should use this hook or astro:build:start, use astro:build:start instead.

'astro:build:setup'?: (options: {
  vite: ViteConfigWithSSR;
  pages: Map<string, PageBuildData>;
  target: 'client' | 'server';
}) => void | Promise<void>;

Previous hook: astro:build:setup

When: After a production build (SSG or SSR) has completed. Why: To get access the SSR manifest, this is useful when creating custom SSR builds in plugins or integrations.

'astro:build:ssr'?: (options: { manifest: SerializedSSRManifest }) => void | Promise<void>;

Previous hook: astro:build:ssr

When: After a production build (SSG or SSR) has completed. Why: To access generated routes and assets for extension (ex. copy content into the generated /assets directory). If you plan to transform generated assets, we recommend exploring the Vite Plugin API and configuring via astro:config:setup instead.

'astro:build:done'?: (options: { pages: { pathname: string }[]; dir: URL }) => void | Promise<void>;

Type: { pathname: string }[]

An array of all generated routes. This currently includes the pathname alone, though we plan to include metadata in the future. Note: this will be empty when using an SSR adapter!

Type: URL

A URL path to the build output directory. We wrap the path in a URL object for easier parsing. If you just want the path as a string, try dir.pathname 🙂

All integrations are run in the order that they are configured. For instance, for the array [react(), svelte()] in a user’s astro.config.*, react will run before svelte.

Your integration should ideally run in any order. If this isn’t possible, we recommend documenting that your integration needs to come first or last in your user’s integrations configuration array.

Combine integrations into presets

Section titled Combine integrations into presets

An integration can also be written as a collection of multiple, smaller integrations. We call these collections presets. Instead of creating a factory function that returns a single integration object, a preset returns an array of integration objects. This is useful for building complex features out of multiple integrations.

integrations: [
  // Example: where examplePreset() returns: [integrationOne, integrationTwo, ...etc]
  examplePreset()
]